The Snapping Turtle, Chelydra serpentina – Part I, Natural History and Behavior in the Wild (with notes on size records)

On May 7th of this year a fisherman in North Carolina caught a snapping turtle that is reputed to be 85 pounds in weight. If the weight proves accurate, this animal would be the largest of the species yet captured. There is an 86 pound animal on record, but this represented a “captive weight” (as those of us who have kept “snappers” know, they balloon in weight quickly in captivity).

The story sparked memories of large snapping turtles I have known, and once again brought to mind how spectacular these relatively common creatures are. We tend to take them for granted here, but they make quite an impression to the uninitiated – hatchling snapping turtles are all the rage in the pet trade in Japan, being described in the media as “tiny dinosaurs” (not far off, in my opinion!).

Until this month’s catch, the largest wild-caught snapper on record was a 76 pound animal (the carapace measured 22 inches) taken from a deep lake in the northeastern USA. The vast majority of very large snapping turtles come from the northern parts of their range (the same holds true for their gigantic cousin, the alligator snapping turtle, Macroclemmys temmincki). As an indication of just how rare such creatures are, consider the following – a review of commercial turtle fisherman’s records show that of 84,000 adult turtles reported, only 160 topped 50 pounds in weight. Of these, only 4 weighed 60 pounds or more. These largest individuals were all males – the heaviest female known tipped the scales at 44 pounds.

Relatively small ponds on Long Island, NY have produced some giants – two that I worked with weighed 54 and 63 pounds when captured. The heavier of these, now a massive 80 pounder, is on exhibit at the Cold Spring Harbor Fish Hatchery (http://www.cshfha.org/).

Of the many large snapping turtles that I have encountered in the wild and in zoos, two in particular stand out (a “small” 15 pound white snapper from NJ is also memorable). Both were found wandering on land (highly unusual) near the Bronx River, in the heart of the Bronx, NY, and showed evidence of recent battles with (most likely) even larger males. The first was delivered to a friend who does animal rehabilitation from his facility in NYC. In order to check the turtle for injuries, we put him on the sidewalk and commenced to hose him off. As the turtle lumbered down East 4th Street, I was, as is usual in such situations, treated to interesting observations of my fellow New Yorkers – some gathered and traded stories while others walked briskly around it as though the 45 pound monster were no more than an upturned garbage can barring their progress!

The second turtle weighed 49 pounds, but was quite emaciated due, I believe, to a severely injured lower jaw that had healed but limited his ability to feed. I installed this fellow in a large outdoor pond near the Bronx Zoo’s reptile house. He soon learned to respond to the sound of my palm striking the water, and would gingerly take a trout (yes, he was spoiled!) from my hand. As they say “Don’t try this at home!” – snappers, even long-term captives, have notoriously well-developed striking abilities, and can cause severe damage injuries (this animal was prevented from doing so by his damaged jaw).

I have worked with most of the giants of the turtle world – leatherbacks, Galapagos and Aldabra tortoises, giant Asian soft-shells and alligator snapping turtles – and will write about them from time to time. For now I’ll pass along some more information about snapping turtles in the wild, and address their care in captivity in Part II of this article.

RANGE
Most of southern and eastern Canada and the United States, east of the Rocky Mountains; subspecies range from Mexico to Ecuador. Widely introduced – California, Nevada and other states in west USA, Japan.

HABITATShallow streams, swamps and ponds to deep lakes and rivers; ponds in city parks and on farms. Some populations inhabit brackish water (tidal rivers and marshes) and have evolved a means of excreting excess salt (Note: I live near a population of these remarkable “salt water snappers” and will report back on them in the future). Rarely leaves the water except to lay eggs; often basks while floating at the surface.

STATUS IN THE WILD
Often the most common turtle within its range and still to be found in quite large cities, yet threatened by collection for the food trade in some areas. In NYC, is relatively common in Central Park, the Bronx River and most other sizable bodies of water; widely farmed. Introduced populations severely impact native turtles and other wildlife.

PHYSICAL CHARACTERISTICS
Massive head, powerful jaws and a long neck. The dark carapace (upper shell) is keeled and serrated at the rear edge. The plastron (lower shell) is quite small. The tail is thick, as long as the carapace, and topped with ridges.

LONGEVITY
To 40 or more years in captivity and to at least 24 years in the wild, but potentially much longer.REPRODUCTION
In my experience, most females in NYC and the immediate environs lay their eggs on rainy nights in early June. I am always rewarded by the sight of nesting females on such nights and during the following mornings. If you have a chance to visit nesting sites during the breeding season, please do so. You will not be disappointed – egg-laying is fairly well-synchronized in many areas, resulting in a spectacular emergence of females where populations are large.

Mating occurs throughout the spring, summer and fall. Females lay 25-85 eggs, 1-1/8 inches in diameter, in a self-dug hole. Nesting sites are generally in open locations. Females often choose newly dug earth, i.e. dirt piles at construction sites (how they unerringly locate such piles, I do not know – but it is a quite definite choice in my experience).

Incubation takes 9-18 weeks, depending upon weather conditions. In the northeast, hatchlings may over-winter in the nest and emerge in the spring. Females can retain sperm and lay fertile eggs for years after a single mating.

The young, jet black in color, forage for insects, worms and carrion in shallow water, and often remain buried beneath the mud with only the eyes and nostrils exposed (as do adults). Hatchlings are preyed upon by large fish, bull frogs, wading birds and other turtles.

DIET
Nearly any animal within their habitat – fish, frogs, smaller turtles, snakes, insects, snails, crayfish, carrion, muskrats and other semi-aquatic mammals; also take crabs, mussels and clams in tidal streams. A 30 pound individual in a pond at the Bronx Zoo once killed an adult mute swan, and I know of a 10 pound turtle that tried to drag a full grown Canada goose below the water’s surface! Some vegetation is taken as well. Often caught on fishing lines.

11 comments

This is a very nice article with some interesting information. I’m glad to see that others have worked with snapping turtles in NYC. I’m currently working on a study of snapping turtle populations in the Bronx, including populations in the Bronx River, Pelham Bay Park, and Van Cortlandt Park. As of 8/18/09, I’ve collected data from 205 individual snapping turtles throughout the Bronx, and the largest specimen found thus far had a 17.5″ carapace and weighed 48 lbs, from Van Cortlandt Lake. If you have any more historical records similar to the ones you wrote about here, they would be of great interest to me and I would appreciate it if you could share them. I’d be happy to share some of my findings as well. I hope to hear from you soon.

I’m very glad you wrote in, urban wildlife is a lifelong passion for me. I see that you work at the Bronx High School of Science…I was a student there many years ago; I recall giving Ken Bobrowsky site localities for brown (DeKay’s at that time) snakes on various Bronx streets, and combing the abandoned buildings in Mott Haven and other then blighted neighborhoods following up reports of black racers (I saw a great deal that I did not expect, much that I’d like to forget, but no racers!).

I like to think that the 48 pounder you mention may have been stalking Van Courtland Lake when I roamed there in the 60’s… very good to hear that animals like that are still there, and that there is someone interested in them – we get to used to snapping turtles, they really are quite incredible; I can tell you they make quite a stir in other countries.

I’ve handled hundreds of Bronx snappers in my time; I often went to a favorite nesting area on the grounds of the Bronx Zoo on the first rainy night in June, which invariably brought out legions of nesting females. Just before I left the Bronx Zoo, an “educational riverwalk” was constructed right at the nesting site, completely destroying it. I was furious – all the more so because a “turtle nesting graphic” was positioned right at now defunct site! I was able to arrange some modification, but the site is no longer viable; a series of waterfalls limits the population’s ability to re-adjust.

The turtles I mentioned in the article were the largest I’ve seen from local waters; I see huge ones regularly in LI estuaries, where I’m sure they are bulking up on crabs, mussels and the like, but have not had my hands on any- would make a great project.

Have you looked at any from tidal areas around the city?

I have notes on most of the wildlife that frequents the BZ, including species lists for fishes, herps, birds, mammals, etc., if you ever have any need. Tons of notebooks as well, but need to go through all and organize some day. John Kiernan’s The Natural History of NYC contains a few good observations, including the story of a large snapper that killed a mute swan on zoo grounds.

Just as an aside, of the 160 50pound+ plus turtles taken by the collector mentioned in this article, 22 came in a single day, from a deep, clear lake in NH! I have a connection to that person, through a mutual friend…I really must look into that some day.

Just popped into my mind – a visitor to the BZ , obsessed with raising bullfrogs, showed up with a photo of his prize (raised in Georgia) – 10 inches snout-vent length (over 20” with legs) and 4.5 pounds – and not obese! His secret was a crayfish-heavy diet (for himself and the frog!).

I would greatly appreciate any information/reports you might be able to send, and any updates. Please also let me know if you need anything from me. I’d love to feature your work in an article at some point as well.

Frank,
I recalled sending you a message a while back, and finally stumbled on your site again. I’m sure your interested in an update on the snapper research. It went very well, with tons of significant findings. I have quite a few publications coming out of it, ranging from papers on deformities to a new trapping method developed during the study, which one day allowed me to get 9 snappers in a single trap! I won the Young Naturalist Award, a nationwide award form the museum of natural history, based on my project. You can read my initial paper here http://www.amnh.org/nationalcenter/youngnaturalistawards/2010/Erik.html. This was based on my 2009 data. 2010 got me even more significant data, which will be published in a paper similar to the one I gave you a link to. Thats some very interesting info that you gave to me about the Bronx Zoo and such, especially the part about the nesting site. This upcoming summer, there’s going to be more research on Bronx River turtles in conjunction with the WCS. They’re very interested in what I found and theres going to be a more in depth investigation of health, diseases and the like. Also, another thing I’m working on is a paper about Bronx Herpetology, as well as something about NYC herpetology as a whole. Any records you have, present or from years ago, would be a huge help. You mentioned that you have a list of herp species that have been found on zoo grounds, that would be extremely useful to me. Feel free to send me an email to discuss. I’m looking forward to speaking with you about NYC herps. Take care

Frank or Eric,
Is weight the only criteria for snapping turtles ?
We found a dead one in the saw millriver with a carapace of about 30 inches, 1 1/2 years ago that is in the hands of a taxidermist and I can’t get him to return it. only weighed 36 lbs, his estimate. also estimated a female about 100 years old.
What are your comments on this ?
Fred

Thanks for your interest in our blog and for passing along your thoughts. The largest snapper in a study of appx 85,000 animals (commercial trapper) measures 22 inches, and I know of no others that have exceeded that, so 30’ would be most unusual, although perhaps not impossible.

Re the taxidermist’s estimates – female snappers are a good deal smaller than males, and do not get anywhere near even the 20” inch mark. Age cannot be estimated by size, other than to say it is likely “older than…..” because of the overwhelming influence of diet on growth rate. Growth rings on the shell fade after 20 years or so, especially in snappers, and so are not an accurate means of estimating age.

Get that turtle back!…you’ll be the turtle biologist’s “man of the year” if it exceeds the magical 22 inch mark!

Just helped a 10-12 lb male find a hole in the fence through to the Split Rock Golf course in Pelham Bay park Bronx, he was not happy about being handled, but the 100 yards of solid fence it no longer has to try and poke through should save it some energy.

There used to be a small amount living in the outflow from the course near a little bridge on the nearby horse trail, but in the past 10 years or so silt has built up and that area is only occasionally flooded, and is being choked out by Phragmites..

Thanks for your interest in our blog. Nice to hear this story…Pelham Bay was one of my favorite stomping grounds, many memories for me. I may know the spot you mention.

Snappers are holding on despite changing habitats as you describe, but getting harder each year. Several years ago a major nesting area (dozens of females) was destroyed by construction of a “river walk” on the grounds of the Bronx Zoo, just above the waterfalls as the Bx River enters the zoo. I was working there at the time, fought it but lost. The turtles still try to nest there, but are now concentrated into an unsuitable area, and aalmost all of the eggs are taken by raccoons.

Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

My name is Richard hunt. Me any my daughter just managed to pull a 59.5 pound snapper out of a local pond in massapequa. This turtle is well known and always there. I also attempted to rescue a smaller snapper that fell over waterfall. He now resides in the brackish 10 by 10 area will he survive? I would like to rescue him and put him back in lake . There is a great population of nesting females in this lake each June . I would be happy. To share with you…

Snakes army main interest and would like to know if there are any black rat milk or racers in Nassau county. I know of a hognose population. Of jones beach….any input on the populations of these constrictors would be great. I am also interestd in learning about these zombie eastern box turtles in isolated areas not able to if d a mate ( Nassau county again)

Thanks for the interesting observation; that’s quite a large turtle; Nassau has yielded a number of surprisingly large snappers…I’m guessing this is due more to the fact that there are more people out and about than anything specific to the habitat, but there are no studies on point. Snappers do occur in tidal areas of rivers, estuaries, etc…some populations are specifically adapted to excrete salt, etc.; whether or not the individual you mention would survive depends on the specifics of the habitat it is in now…I imagine it will try to leave such a small area in time.

Each of those snakes should occur in Nassau, but as far as I know they are not often recorded ..populations likely very small and fragmented; the larger preserved areas and private estates on the north shore would be most likely to support them.

Not sure what you mean re box turtles, but the outlook for them in Nassau is bleak; best places would be as for snakes, but box turtles are even less likely to be holding on in decent numbers.

About Frank Indiviglio

Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.

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